Astronauts face ‘space anemia’ as they leave Earth; understand

Space travel is known to be hard on the human body, but new research has revealed just how hard it hits red blood cells.

When we are on Earth, our bodies create and destroy 2 million of these cells per second. In space, astronauts experienced 3 million red blood cells destroyed per second, resulting in a 54% greater cell loss than people on Earth experience, according to a new study.

A lower red blood cell count in astronauts is known as “space anemia”.

“Space anemia has been reported consistently when astronauts return to Earth since the first space missions, but we didn’t know why,” said study author Guy Trudel, a rehabilitation physician, researcher at Ottawa Hospital (Canada) and professor at the University of Ottawa in a statement.

Researchers took breath and blood samples from 14 astronauts before their six-month stay on the International Space Station. Astronauts also took samples four times during their flights. The researchers also collected blood from astronauts up to a year after spaceflight.

The flights of the 11 men and three women took place between 2015 and 2020. The results were published on Friday (14) in the journal Nature Medicine.

a surprising discovery

When astronauts are in space, they experience a shift of body fluids towards the upper body due to lack of gravity. This results in increased pressure on the brain and eyes, causing cardiovascular problems and a loss of 10% of fluid in your blood vessels.

The researchers believed that spatial anemia was the body’s way of adapting to changing fluid, resulting in the destruction of red blood cells to restore balance. They also thought that the loss of red blood cells was only temporary, re-establishing itself after the astronauts spent ten days in the space environment.

Trudel and his team discovered a surprising result: the space environment is the real culprit.

“Our study shows that upon reaching space, more red blood cells are destroyed, and this continues throughout the duration of the astronaut’s mission,” he said.

The research team developed ways to measure red blood cell destruction, including measuring the amounts of carbon monoxide detected in astronauts’ breath samples. Each time a molecule of hemoglobin, or the signature red pigment in red blood cells, is destroyed, a molecule of carbon monoxide is created.

The team was unable to directly measure red blood cell production in astronauts, but they hope the astronauts experienced the generation of extra red blood cells in response to increased destruction. Had this not occurred, all astronauts would have suffered the effects and health problems associated with severe anemia while in space.

“Fortunately, having fewer red blood cells in space is not a problem when your body is weightless,” Trudel said. “But when he returns to Earth and potentially other planets or moons, anemia that affects his energy, stamina and strength could threaten the mission’s objectives. The effects of anemia are only felt when we land, and we have to deal with gravity again.”

long term effects

Upon return to Earth, five of the 13 astronauts were diagnosed as clinically anemic. One of the astronauts had no blood draw after landing.

Follow-up samples taken from the astronauts showed that space anemia is reversible, because the red blood cell counts progressively returned to normal between three to four months after the return.

However, samples taken a year after the astronauts landed on Earth showed that the rate of red blood cell destruction continued to increase, about 30% higher than before their space flight.

The researchers believe this suggests that long-duration space missions could result in structural changes impacting red blood cells.

The findings are the first published results from Marrow, an experiment that examines bone marrow health and blood production when astronauts are in space.

The results underscore the importance of screening both astronauts and space tourists for health conditions that could be affected by anemia and any problems during missions. A previous study by Trudel and his team also found that longer space missions worsen anemia.

For now, it is uncertain how long the human body can withstand a higher rate of both destruction and production of red blood cells.

In order to combat this risk, the researchers suggest that astronauts’ diets be changed to support better blood health.

The lessons learned from this research could also be applied to anemia patients on Earth, especially those who experience it after illness and prolonged bed rest. While the direct cause of this type of anemia is unknown, it may be similar to what happens in space.

“If we can figure out exactly what is causing this anemia, then there is potential to treat or prevent it, for both astronauts and patients here on Earth,” Trudel said. “This is the best description we have of the control of red blood cells in space and after the return to Earth. We were surprised and rewarded by our curiosity.”